Fan economizer



Oct. 24, '1939. v wQcARPENpl-:R Re. 21,243 I FAN EcoNoMIzER 4 Original Filed Aug. 8,' 1934' INVENToR M7/fam Cb/panda* BY E v ATTORNEY Reissued Oct. 24, 1939 UNITED s TATEs PATENT OFFICE FAN ECONOMIZER William Carpentier, New Brunswick, N. J., assignor, by mesne assignments, to Carrier Corporation, Newark, N. J.,

aWal'E a corporation of Del- Original No. 2,101,983, datedxDecember 14, 1937,

Serial No. 738,950, August 8, 1934. Application for reissue November 15, 1938, Serial No.

11 Claims.

ordinately with the circulation of air as applied y to and carried out in atmosphere wherein produce is stored or handled.

The problem of preserving food products, such as meats, fruits and vegetables, involves a number of factors Whose proper coordinationsets up a special problem not encountered in carrying out air conditioning processes in the industrial field generally. The produce has a tendencyto give off moisture. This moisture, in the case of meats, and some vegetables, for example, must be removed to some degree, otherwise, the surface will become slippery or. slimy; or, at times, covered with mold. Yet, if the moisture is removed too fast, the outside tissue or covering will tend to harden. Also, the air circulation must be controlled not only to avoid too rapidk evaporation, but also, defeat tendencies to discoloration. In the case of other vegetables and fruits, moisture is also an element whose formations, etc. Yet, the removal must not be so prevent softening, mold formation, soggy condition, etc. Yet, the removal must not be so rapid that a dry and desiccated condition results.

In addition to moisture removal, the produce must be subjected to air properly refrigerated, whose temperature does not fluctuate more than two or three degrees. For example, in the case of fresh meats, the desirable temperature range is between 30-40 degrees Fahrenheit, but each specie..l of meat requires a specic temperature within said range, and the fluctuation from said specic temperature should not be more than a degree or a degree and a half either side. In the case of fresh vegetables, and fruits, the desirable temperature range is between 3l degrees Fahrenheit and 56 degrees Fahrenheit, but each species or variety of species requires conditioning at a specific temperature Within'said range, and the fluctuation from said predetermined point should here, too, be limited to a degree or degree and a half. In order that the air at these temperatures be capable of effective preservation of produce, the moisture content with re- Y spect to desired temperatures, i. e., the relative humidity, must also be controlled within predetermined limits. ---Thus, for meats, it is desirable that the relative humidity at temperatures between 30 degrees F. and 40 degrees F., range between 90-85 per cent, depending upon the speciiic temperature employed. In the case of fresh vegetables, where the temperature range is between 31-56 degrees F., it is desirable that the relative humidity be limited respectively to a range between 90-75 per cent, the specic relative humidity being produced and maintained at a percentage most beneficial for the specic` temperature employed; and the same figures apply, generally, in the conditioning of fresh fruits.

It has been found that, in addition to the control of temperature and relative humidity, it is also essential to move or circulate the air throughout the conditioned area. Furthermore, while this movement is highly benecial under some conditions, it becomes very detrimental under other conditions, especially when the temperature or relative humidity factors are not at the required points (making allowance for negligible uctuation) for maintaining necessary conditions. For example, if the air assumed a higher temperature than that prescribed, then the relative humidity would tend to fall and descend below the prescribed percentage. Under such conditions, as when the refrigeration is inoperative, which is the case at stated periods under normal operation, an active circulation of air would tend to dry out or desiccate the produce, with detrimental results both to quality and appearance. Therefore, in addition to the control of temperature and relative humidity, applicant coordinates with these actors the control of air motion.

A feature of the invention, therefore, resides in the control of air motion coordinately with the control of temperature 'and relative humidity in systems for preserving and conditioning produce. Another feature covers a system for governing, automatically, the iiow of conditioned air, so that air movement will be assured when the air is .at a desired condition, and air movement halted when the condition of the air is unsatisfactory for the preservation of produce. Y

Further features making -for improved methods in the preservation o'f perishable products will be more apparent from the following de- Fig. 2 is a diagrammatic view of an arrangement illustrating one method of controlling air movement in a refrigerator such as that of Fig. l, and

Fig. 3 illustrates a temperature responsive control for operating applicants fan economizer.

Considering the drawing, similar designations referring to similar parts, numeral 3 represents a refrigerator of orthodox construction, having insulated walls 4, one or more doors 5, and beams 6 for supporting or accommodating produce. In Fig. 1, where a meat refrigerator is particularly illustrated, hooks I `are shown for hanging carcasses 0r cuts of beef. In other arrangements, any desired holders or supporting means may be used on which not only meats, but vegetables and fruits may be stored and preserved or conditioned.. The construction of the refrigerator or manner of accommodating produce forms no part of this invention, and the figure is intended to be diagrammatic. At the upper part of the refrigerator, adjacent the ceiling level, is suitably mounted an apparatus for supplying refrigerating effect and-causing a circulation of air inthe refrigerator. Such an apparatus is usually a self-contained unit structure comprising a lseries of coils to which a refrigerant or refrigeratng medium may be supplied directly from the refrigerating machine or a cooler served by the evaporator. A motor driven fan is mounted on the` unit, so that the coils, fan, motor and casing structure form a single integral self-contained piece of apparatus adapted to be handled in one unit. This is designated by the numeral 8 in Figs. 1 and 2.

In Fig. 2, the unit 8, which we shall term a cold diffuser, is-shown in combination with a refrigerating machine and control means for governing the action of the fan. The refrigeration and control mechanism may be located outside of the refrigerator or otherwise conveniently positioned. The refrigerating machine 9, of suitable design, has a motor I0 for driving compressor II which discharges the compressed refrigerant through line I2 into condenser I3, from which the refrigerant in liquid form goes through shut off valve I4 and liquid line I5 to expansion valve I6, and then through the coils Il. The air, in' passing through the coils, will cause the usual heat exchange between the heat in the air and the refrigerant, whereby the air will be cooled, and the refrigerant gaseed. Gas line I8 connects the discharge from'the evaporater I'I to the compressor. The expansion valve I6, in the arrangementv illustrated, is controlled responsive to changes in temperature in the gas or suction line, which is reflected in line I9. This line I 9 communicates vapor pressure for operating expansion valve I6 from refrigerant in thermal tube 2li, in contact with the suction line I8. The vapor pressure in line I9 vn'll tend to increase or decrease responsive respectvely'to increases and decreases in temperature in the suction line. Connected with gas line I8 is located a fan economizer unit 2l including switch 22 which controls a circuit for motor 24, ar'- ranged to operate fan 25. Push button switch 23 is always on when the system is in operation. As is obvious from the dash-dot Wiring diagram, the circuit for operating motor 2l may be completed or broken by the actuation of switch 22. In Fig. 2, ythe .fan economizer 2| responds to changes in the pressure in line III, which is the vapor pressure of refrigerant in coil I1. As a result, if the pressure should rise, beyond a predetermined point, as would be the case when the refrigeration were cut on, and defrosting completed including evaporation of moisture on the coils, then the control yoperates to break the contacts in switch 22 and hence, break the electrical circuit to the motor, thus stopping the fan.

In Fig. 3, a temperature responsive control is illustrated for operating applicants fan economizer. A thermal bulb 2G, similar in function and structure to 2|) of Fig. 2, is positioned in thermal contact or bond with a tube of the coil 21. As a result, the thermal bulb will reflect the temperature of the refrigerant within the coil and, hence, the surface temperature of the coil. As the temperature rises beyond a predetermined point, which would be the case when the'refrigeration were cut olf and defrosting completed, including evaporation of moisture on the coils, the vapor pressure of the refrigerant in the thermal bulb 26 would increase to cause switch 22 to open, thus stopping fan 24.` The combination of bulb 26, the communicating pressure line and switch 22, shown in Fig. 3, is the equivalent of the fan economizer pressure control generally designated 2l in Fig. 2. Whenthe refrigeration is turned on, the temperature in coil 21 will fall almost immediately to the prescribed level. As a result, this temperature will substantially instantaneously be reflected by a fall in vapor pressure within the line connecting thermal bulb 26 to switch 22 with the result that the contacts will close and the circuit for operating fan 24 be completed.

It is irrelevant whether or.not the control 2| operates responsive to changes in temperature or pressure, and applicant makes no limitation with respect to the specific means employed for breaking the circuit for operating the fan whenever conditions in the enclosure indicate that a movement of air is undesirable.

In practice, the refrigerating machine will be started up and thereupon cause a drop in the temperature and pressure in gas line IB and coil II. This will be reflected by the control 2|. If it is of the temperature responsive type, as in Fig. 3, it will function responsive to the drop in temperature to close the circuit for the fan. If it is of the pressure responsive type, it will similarly operate to close the circuit for the fan. Thus, whenever refrigeration is being supplied, the fan will always operate. however, that the refrigeration machine becomes inoperative, then the coils will gradually defrost, i. e., the frost formation on the coils which builds up due to precipitation and freezing as dehumidiiication is carried on when the re` frigerant is below freezingV temperature, will gradually begin to melt away. When the melt-4 ing process is completed, and the wetcoils commence toV become dry, the refrigerant temperatureand corresponding pressure vin the suction line and coil I'I will rise precipitately. This will cause the temperature or pressure device 2l, as the case may be, to open the switch, so that the fan will immediately becomeinoperative. As a result, further evaporation from the produce will be Vminimized and lowering of relative humidity due to circulation of room air, whose temperature is rising because of absence of refrigerating Assuming,

interpreted as illustrative and not in a limiting sense. V

I claim: 1. A method of conditioning the air ina refrigerator, consisting in supplying refrigeration eiifecil to the air Within the refrigerator, so that a desired air temperature will be maintained therein, actively circulating air in the refrigerator when the temperature of the refrigerant used is below a predetermined maximum and eliminatrefrigerating effect and upon substantially complete defrosting of saidfrozen precipitate.

3. A methodof conditioning air used in re- 25-frigerators and the like, consisting in supplying a volatile refrigerant toa cooling surface, circulating air over the surface to provide an active movement thereof in the conditioned area, said refrigerant being vaporized by absorption of heat from said air, and interrupting the circulation of the air when thegtemperature and corresponding pressureof the vaporized refrigerant circulating proximate said surface rise above predetermined maximum limits.

4'. In an apparatus of the character described, a heat interchanger, a fan for circulating air in contact With the'heat interchanger, means for supplying refrigerant to the heat interchanger, the discharge of airvoverthe heat interchanger resulting in a frosting of the surfaces thereof due to a precipitation of moisture thereon, and

means for causing the fan to become inoperative` when the temperature of the surfaces of the heat interchanger rises above the melting point of said frozen precipitate, before heat from the interchanger may cause the temperature in the area served by the system to rise.

5. In an apparatus of the character described, a heat interchanger, a ian for circulating air in contact with the heat interchanger, means for supplying refrigerant to the heat interchanger, the circulation of air over the heat interchanger resulting in4 a frosting of the surfaces thereof due to a precipitation of moisture thereon, means for interrupting the supply of refrigerant to the heat interchanger, and means for causing the fan to become inoperative upon completion of the defrosting of the heat interchanger subsequent tointerruption of the refrigerant supply. i 6. A method of conditioning the air in a refrigerator, consisting-in supplying a refrigerant to a cooling surface, controlling the supply of refrigerant, actively circulating air over the surface to provide an active` movement thereof in the refrigerator, the circulation of air over the surface resulting in the formation of frost thereon, the interruption of said refrigerant supply resulting in the melting of said frost, and causing the active circulation of air` to cease upon the substantial completion of saidmelting subsequent to the interruption frigerant.

7. A method of conditioning the air in an area wherein perishable produce is stored, consisting in supplying refrigerant to a cooling surface, controlling the supply of refrigerant to the surface. circulating air over said cooling surface,

of the supply of rethe circulation of aircausing a precipitation of moisture on the surface, and interrupting the active circulation of air subsequent to the interruption of the supply of refrigerantto the cooling surface and upon completion of the evaporation of the moisture precipitated on the surface.

8. A method of preserving perishable produce, consisting in supplying refrigerant to a heat exchange surface, actively circulating air in con- `tact with said surface, the -refrigerant being converted from a liquid to a gas and absorbing heat from said air, controlling the supply of liquid refrigerant to the surface responsive to the condition of the gaseous refrigerant leaving the surface, and interrupting the circulation of air in contact with the surface. whenever the temperature or pressure of the gaseous refrigerantleaving the surface rises Aabove a predetermined point. v

. 9. In air cooling apparatus, the combination of a cooling element, means for circulating air in direct contact with said cooling element, and means responsive to a predetermined maximum temperature of said cooling element to prevent operation of said air-circulating means.

10. In air cooling apparatus, the combination of a. cooling element, means providing circulation of air in direct contact with said cooling element, and means responsive to avpredetermined maximum temperature of said cooling element to discontinue circulation of air in heatexchanging relation with said cooling element.

11. In air cooling apparatus, the combination of a refrigerant evaporator, means for removing Yvapor from said evaporator to effect cooling by vaporization of liquid therein, means providing circulation of air in direct contact with said evaporator, and means responsive to a predemined maximum temperature of said evaporator to discontinue circulation of air in contact with said ievaporator.

' wnLmM cARPENDEa CERTIFICATE OF CORRECTION. Reissue No. 21,215. October 2h, 1959.

WILLIAM CARPENBER.

Itis hereby certified that error appears in the printed'specification of the above numbered patent requiring correction as follows: Pagel, first column, line 26, strike out "tions, etc. Yet, the removal must not be so" and insert instead the syllable and words tion on the outer surface requires c removal, to; line 28, for "tion" read tions; page 2, first o olumn, line 28, -for "by the" read by an; and that the said Letters Patent should be read with this oorreetion therein that the same may conform to the record of4 the case in the Patent Office.

signed and Sealed this 26th day of December?, A. D. 1959.

Henry Van Arsde le, (Seal) Acting Commissioner of Patents. 

